Thermostatic switch



B. E. GETCHELL -THERMOSTATIC SWITCH Filed April l0, 1943 Contact 8 has a soldering lug l2.

`Patented Dec. 3K, 1946 THEnMosTA'rIC SWITCH Benjamin E. Gctchell, Plainville, Conn., assigner to The Trumbull Electric Manufacturing Company, Plainviile, Conn., a corporation of Connecticut Application April 1c, 194s, semi No. 482,559

(ci. zooisti 7 Claims. 1

My invention relates to snap action switches actuated by bimetallic members.

The main object is te eliminate the need for grinding and sharpening pivot points of the thermostatic switch.

Another object is to provide a simple reliable device which can be commercially made and readily adjusted.

Another object is to provide a thermostatic switch which can be adjusted without distorting the bimetal member.

Another object is to provide a device which does not readily get out of adjustment.

Another object is to provide a device, the parts gf which can be economically made and assem- Fig. 1 is a plan view of a switch embodying one form of my invention.

Fig. 2 is an edge view of the same.

. Fig. 3 is a rear view of the same.

Fig. d is a plan view of the blank from which the base is formed on a reduced scale.

Fig. 5 shows a, plan and edge view of the contact trip member.

Fig; 6 shows a plan and edge view of the support for the contact trip.

Fig.. 7 is an enlarged detail view showing the means for supporting the contact trip member.

The base l is of sheet metal, for instance steel. The switch contacts 8, S are carried by one end of the base butv suitably insulated from it for in stance by bre washers IIl, II. The stationary The support i3 is preferably of phosphor bronze and riveted to the base but insulated from it and provided with a wire terminal i4 at the back. it may have a small boss i3' projecting into the insulation ll so as to hold the support in proper alinement, the metal base being cut away as at I to avoid contact between the metal parts.

The trip member I5 which carries the movable contact S is preferably of hard brass and hinged to the support I3. A knife edge hinge bearing is elected in a very simple manner. The support I3 has two upstanding posts li formed with bent angle recesses i6 of slightly over 96 angle to receive the sharp cut edges Il formed in blankin'g the trip member from sheet metal and which constitute the pivot or hinge of the trip member I5. The lugs I8 of the trip member beyond the knife edges extend past the posts I4 so as to prevent sidewise displacement. The tail piece IS? extends from the trip member in the direction opposite to the Contact 9 and serves partially to counterbalance the trip member and also to act Vas a stop to limit the opening action by striking against the upturnecl edge of the support. It will thus be seen that the trip member is supported by the very member which acts as an abutment for its open circuit action. This pre vents the stop from changing' even if the main base or the insulating washer should be displaced or warp.

The bimetallic arm 2l has one end riveted to the lug 22 which is formed as an integral part of the base l and oiiset from the end 23 which is bent back over the adjacent top of the base. The other end of the arm 2i is connected by a snap action spring 2t to the trip member l5 between the contact 8 and the hinge line. The bi metallic arm can be so adjusted as to normally hold the circuit closed or open. Preferably an insulating piece 25 is interposed between the arm and the spring.

Adjustment of the bimetallc arm can be readily eected by tightening or loosening the screw 26 which is screwed into the base and engages the underside of the end 23 to bend the end more or less. lt will be seen that such adjustment does not bend or distort the arm 2l at all but does change its position by reason of the movement of the lug il?. with. the end 23. The end is suiileiently resilient to automatically return to ,its former position when released by retraction of the screw.

The type of lnfe edge support of the movable trip member very simple and easy to make as it does not require grinding or fitting of pivot pins or bearings. By bending a part of the blank of the Contact trip member i5 at an angle of 45 to its main anis, the corner of the cut edge Il .formed in blanlring theipiece from sheet metal serves as a sharp edge similar to a knife edge. The angle it formed by stamping the post is made slightly greater than and serves as a l 1. A thermostatic switch comprising a base; a'

trip contact 'member hinged at one end of the and move the return bend and lug of the base for varying the action of the bimetal arm.

2. A snap switch having a sheet metal support with a supporting post bent to form two at angular portions providing an open angle recess slightly over 90, a movable .contact carrying member blanked from sheet metal and bent so as into the angle recess, the corner of this cut edge thereby forming a sharp edge pivot for the movable contact member.

3. A snap switch having a sheet metal support with a supporting post bent to form two fiat angular portions providing an open angular recess slightly over 90, a movable contact carrying member blanked from sheet metal and formed vwith a cut edge sheared at right angles to the adjacent surface and bent so as to present a right-angled corner of said cut edge into the angular recess, said corner. forming a sharp edge pivot for the movable contact member and spring means for normally holding the corner of the edge against the corner of the angular recess.

4. A thermostatic switch comprising a base member having a flat body portion with one end thereof bent backwardly upon but spaced from the body portion, an integral lug portion carried by said bent portion,` a stationary contact carried by said base, a movable contact, a bimetal arm having one end fastened to said lug portion and its other end connected to said movable contact for actuating the same and means for adjusting the position of said arm including a screw member carried by and movable through said base into the space between said bent portion and the base and directly/,engaging said bent portion for adjusting the relative position of the arm and base.

5. For use in an electric switch having a stationary support formed with angularly disposed fiat portions providing an open angle recess at least slightly over and of substantial length, a movable member having its body blanked from sheet metal, said body having end portions disposed in the same plane, one of said end portions carrying a contact member and the other end portion acting as a stop and counterbalancing member, the portion of said body between said end portions being bent out of the plane of said end portions and being provided with an elongated edge portion cut at right angles to the plane of the adjacent portion thereby forming right angled corners, said member and support beingso positioned relatively that a sharp corner of said cut edge portion provides a knife-edgedpivot for the movable member in the open angle recess of the support.

6. In an electric switch, a stationary member formed of sheet metal with an elongated open angle recess in one surface formed by bending one portion with respect to the adjacent portion, the walls of said recess extending at an angle of more than 90 with respect to each other, a movable member pivoted in said recess, said movable member being blanked from sheet metal and having. an. elongated edge cut at substantially right -angles to the adjacent metal so as vto provide a sharp-.corner at one surface, said corner being seated in said recess andserving to support said movable member in the manner of a knife edge.

'7. A thermostatic switch having a sheet metal support with two upstanding integral posts bent to form angular recesses, a sheet metal trip contact member having spaced-apart cut vedges forming knife edges seated in said recesses, said edges being formed by shearing the metal at right angles to the main surface and a bimetal arm having one. end stationary and a spring extending between the posts and connecting the other end of the bimetal arm to the trip member and holding the cut edges in the recesses.

BENJAMIN E. GETCHEIL. 

